Telemarketers generally attempt to deliver information messages by telephone to live consumers. In the last decade, automatic telephone answering machines have become a popular addition to most homes and businesses. Telemarketers are usually reluctant to leave information messages on these answering machines. Thus, it has become more popular than ever for the telemarketers to use computers which will detect conditions that an answering machine is receiving the call so that the call can be dropped(hung up). See for example: U.S. Pat. No. 4,356,348 to Smith. These dropped calls can be quite significant when considering the number of answering machines and undelivered information messages that occur.
Attempts have been made over the years to overcome the problems with delivering messages to telephone answering machines. See for example U.S. Pat. No. 4,667,065 to Bangerter; U.S. Pat. No. 4,941,168 to Kelly, Jr.; U.S. Pat. No. 5,371,787 to Hamilton; U.S. Pat. No. 5,430,792 to Jesurum et al.; and U.S. Pat. No. 5,581,602 to Szlam et al. However, these patents are generally are limited to sensing audio signals generated by the answering machines and and do not cover all the types of answering machines which start recording after different selected delay times. For example, many of these devices commence playing a recorded message based on mistakenly detecting when the "beep" has occurred. The false "beep" signal is a common problem for real callers trying to leave messages on answering machines. Furthermore, these patents do not fully analyze the connected calls in order to utilize preselected delay times to deliver and play recorded messages.
Message delivery systems which deliver a recorded message to an answering machine must solve the problem of determining when to "Launch"(begin playback of) the prerecorded message. Conventional systems rely on a timer to determine the moment to begin playback of the recorded message. Typically a timer is initiated once the determination has been made that the call has been answered by a machine. Message delivery systems which rely on timed delivery experience a high percentage of truncation of the recorded message. This is a result of the system begins to play of the recorded message BEFORE the answering machine starts recording.
Another serious problem with timer based systems is that many answering machines will "hang up" on the system before the message launches. This is due to a "vox" function in many answering machines which allows them to stop recording after they detect several seconds of silence. If a timer based system waits too long before launching the message, the called answering machine may have already hung up before the message playback begins.